<svg
  class="w-100"
  width="800"
  height="400"
  xmlns="http://www.w3.org/2000/svg"
  role="img"
  preserveAspectRatio="xMidYMid slice"
  focusable="false"
>
  <title>占位图</title>
  <rect width="100%" height="100%" fill="#777"></rect>
  <text x="50%" y="50%" fill="#555" dy=".3em">占位图一</text>
</svg>
